DIY Riser Block for 6" x 26" Import Mills (Grizzly, Enco, Harbor Freight, etc.)

Neurotic-Hapi-Snak

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Not to be a spoil sport, but you can buy a 6" dia, 12" length piece of ductile cast iron for $200 from McMaster-Carr, that's enough to make a riser plus a spacer to move the head away from the column further.
 

Tmate

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Not to be a spoil sport, but you can buy a 6" dia, 12" length piece of ductile cast iron for $200 from McMaster-Carr, that's enough to make a riser plus a spacer to move the head away from the column further.

Just trying to come up with a new way of attacking the problem. I like doing that.
 

Neurotic-Hapi-Snak

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Would just hate for you to spend all that money when you could do it a better, easier way, for about the same. Plus I thought those were the standard cast steel flanges.
 

Shootymacshootface

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I’m not familiar with that mill, but curious (nosy?). I don’t see any obvious (to me) adjustments for head nod and tilt in the pics. Does it have such adjustments like the Bridgeports that I’ve seen, or will you need to shim the risers or make other adjustments to tram it?

Also, will the surface friction between the riser layers be enough to keep them from moving relative to each other during heavy cuts and such? Are you sacrificing rigidity for space or will it have an insignificant effect?

Tom
I was curious about this as well, until I watched a Stefan Gotteswinter were he trammed in an RF25 clone using epoxy. I guess the conventional method is scraping in the base where the column bolts to it.
The spacer is a great idea, but if you can't get it trammed in pretty close, you can forget about using a fly cutter.
 

Neurotic-Hapi-Snak

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I was curious about this as well, until I watched a Stefan Gotteswinter were he trammed in an RF25 clone using epoxy. I guess the conventional method is scraping in the base where the column bolts to it.
The spacer is a great idea, but if you can't get it trammed in pretty close, you can forget about using a fly cutter.
Plus you'd be adding in 12 more mating surfaces that could add error rather than two with a solid riser. Quick and dirty is to use shims, proper way is to scrape both surfaces so that they not only match each other but are perpendicular to the axis of rotation. That way you won't have any error show back up when you rotate the head.
here's another way to do it, with dimensions:

I'll be making mine so that the bolts go all the way through into the t-nuts in the base. I have 4 or 5ft of allthread (M10x1.??) so that I can reuse both the t-nuts and the acorn nuts at the top. The allthread will be captured by the riser so it will rotate with the head.
The problem with that design is you're sacrificing quite a bit of rigidity by using a 3" diameter pipe rather than a 6". Best design would be to use a riser of 6" (or more) in diameter with the bolts going from the turret to the column through the riser. That way you put the riser in compression and the bolts into tension, limiting how much each can flex.
 

Tmate

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I was curious about this as well, until I watched a Stefan Gotteswinter were he trammed in an RF25 clone using epoxy. I guess the conventional method is scraping in the base where the column bolts to it. The spacer is a great idea, but if you can't get it trammed in pretty close, you can forget about using a fly cutter.
Would just hate for you to spend all that money when you could do it a better, easier way, for about the same. Plus I thought those were the standard cast steel flanges.

I realize this is a somewhat impractical exercise, and for me the fun is trying something new. If it doesn't work, I'm out about the cost of a couple of meals in a good restaurant. I can easily pull the flanges back out and the mill will be none the worse for it.

There have been many approaches to making these risers. The most common, of course, is to machine it from a solid round bar. Others have welded flanges onto either end of a tube. Some have used individual tubes between end flanges. I don't know of anyone who has tried this method. It may well not have sufficient rigidity.

The flanges will all be pinned rather tightly together with 3/4" drill rod passing snugly through their original bolt holes. I'm hoping this, plus the weight of the head, plus the clamping of the three bolts will hold it firmly. There is no head nod adjustment on these mills, just side to side. I could possibly work one of the flanges lightly to tram the nod.
 

Neurotic-Hapi-Snak

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Best way would be to face them all off, ream the holes to a precise size, e.g. 25/32" or 49/64" , but slightly under sized. Then either heat each flange till you can fit a rod of the correct diameter through and allow them to cool and contract on the rod, or you could use a press to force the rod in. You want to make it so they effectively become one piece, thereby eliminating all those mating surfaces. Or you could weld them together. Then you want turn or mill the top and bottom faces so they are parallel.
 

mattthemuppet2

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The problem with that design is you're sacrificing quite a bit of rigidity by using a 3" diameter pipe rather than a 6". Best design would be to use a riser of 6" (or more) in diameter with the bolts going from the turret to the column through the riser. That way you put the riser in compression and the bolts into tension, limiting how much each can flex.

I linked that build thread as it's a good source of dimensions without having to take the top of your own mill off :) I'll be making mine with a piece of 1/2" thick 6" OD and 4" height flat belt pulley (if that's what it is!) that I'll weld a piece of 1/2" round to. All thread to go through it into the t-nuts in the main casting.
 

Neurotic-Hapi-Snak

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Another thing to consider is material choice. Although steel is easier to source, it doesn't dampen vibration like cast iron, so a riser made of steel would only dampen vibration through mass alone. Dampening vibration is important for machine tools, especially small ones that lack mass.
 

jwmelvin

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But remember too that the bolted joints of a riser will also themselves absorb vibration. Although it’s hard to say the relative effect of that versus material choice (and they are not mutually exclusive), the damping from bolted joints can be quite significant.
 
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